A Monolithic CMOS-MEMS SoC with 1.8 mm/s and 2 mK Resolution for Flow and Temperature Sensing via a Microcantilever Array

This paper presents a highly sensitive CMOS-MEMS system-on-chip (SoC) for multiparameter sensing, achieved through the monolithic integration of a capacitive microcantilever array with on-chip signal processing circuitry. Fabricated in a 0.18 µm 1P6M CMOS process with an in-house developed post-CMOS technique, the SoC offers high sensitivity, compact size, and excellent resolution. In temperature sensing mode, the SoC achieves a sensitivity of 25.1 kHz/°C across a linear range of 20-100 °C, with nonlinearity below 0.3% of the full-scale span (FSS). In flow sensing mode, the frequency output follows a quadratic relationship with velocity up to 130 m/s, yielding a linearized sensitivity of 133.5 Hz/(m/s)² and a maximum sensitivity of 32.76 kHz/(m/s) at 130 m/s. Noise analysis reveals that the SoC exhibits a minimum Allan deviation of 14.8 Hz, corresponding to a minimum detectable flow velocity of 14.8 mm/s, with resolutions of 29.6 mm/s and 1.8 mm/s in the low- and high-flow regimes, respectively. Meanwhile, the temperature sensing resolution reaches 2.3 mK, while light-induced thermal tests also confirm the SoC's ability to detect subtle temperature variations, further demonstrating its ultrahigh sensitivity. The demonstrated performance, combined with a high level of integration, positions the proposed CMOS-MEMS SoC as a promising candidate for miniaturized, high-precision sensing in environmental and biomedical applications.